Receptacle closure



Dec. 15, 1953 M. B. BEAUBAIRE ET AL 2,

RECEPTACLE CLOSURE 3 Sheets-Sheet 1 Filed April 14, 1953 ATTORNEY Dec. 15, 1953 Filed April 14, 1953 M- B. BEAUBAIRE ET AL.

RECEPTACLE CLOSURE I 3 Sheets-Sheet 2 INVENTORS ATTORNEY 1953 M. B. BEAUBAIRE ET AL. 2,662,656

RECEPTACLE CLOSURE Filed Apfil 14, 1955 s SheetsSheet s yup ////////////I////////////////,: I

' MRQM ATTORNEY ////I////l//////////////Il/////////A Patented Dec. 15, 1953 oFFlcE itsasss I ititiififiiibm anesthelii ie Taiwanese n Strind; Minneapolis, Minn. fiiiutfltii 14, 1956: si iif 1331 1243171 1 501E653; (01. 215-51) This invention relates-t6 clos'ure nie'ansland more particularly to closureim'ans' for recep tacles for beverages for human consumption: The closure means in: accordance" with the invention' is admirably suited'for bottlesfor carbonat edbeverages; beer; and the like; which are maintained under piessix're;

At the present time; great use'is: made of. old-f sures known as crown ca psr. These,- front, the standpoint of durability and"- co'st have proved quite satisfactory: Howevn beeausethe' pressure or the gases within thereceptacles is consantly exerting its force in the direction or re% movai of the cap; crown aps seldo'm prevent leakage of the gases and 'a consequentwdiminism in'g'of the pressure within? Moreoventheii struc' ture is such that, iromearemoved toflpermitpa" portion of the contentsi ofthe' receptacle tolbe withdrawn; they cannot; .when replaced; provide a leak'proof closure as willprevent escape of the gases. Accordingly, the beverages soorrybecoihe fiat.

The present invention approaches the'problem from the standpoint that ansatis f actorycclosure could well make 1158"Offih81fl1885111'8 of the gases within the receptacle 1 in:- assistingg-to maintain theclosure in sealing position: With this 'deside eratum in view; the inventionaasr' applied to a* beer bottle, for examplei-inakes .usie of-= acohiparativelythin flexible disk whichi is forced-"into" an annular, angular grooye' inthe inner surface of the neck of theibottlen'ear the niouthy? the disk beingv of greater diameteffithan' the groove so that thedisk;when in position inithe' groove; is dished inwardly. Inthatp'ositibnnthe ,pres' sure within tends toforce the-peripheral-edge of the disk tightly against"-thesurface of the groove. V

While the general ide'a: oi -siich-= a disk' stopper has been known for manyyears: theirzusevhas' never provedsatisfactory in'*practice1for a num'gber of reasons: Therequirements oi" a-satisfac torydisk stopper of 'thatgeneral type are many and; until our presentrimfientiorr, n suchstopper has been known oi 'proposedwhieh 'will' meet them: V J. N n... ,1- N,

As relating-"toclosuresiox bottled beer, for examp1e-t e i ksto er fi st-grmustibe stron enough and stiff -enouglyandfbe1- solodgfed with-1 in the neckof-the-bottleradio"refiistitheinternal pressures caused byi the been; tending to; force out the stopper; Thes v internaltpre ss ures are Often as hi hest in). .imo h teaflasi heated durin gjpa'steur zation to 50 F. and to' must be capable of resisting considerable bending in order to permit its insertion and removal, whil not crabking' or tearing from the stress thus imposed.

Carbonated beverages areoft'en subjected to temperatures rangingfroin' below zero Fahrenheit to pasteurization ..temperatures, or higher. The disk stopper'iand its relationshipto the grodveinxthe' bottleneckimust be such that the characteristics-mentionedwilLnot. be adversely afiecte'dzby such'temperature-changes. The disk not'only'xshouldnotibecomebrittle or soft when subjectedmoi' varioustemperatures. normally encountered; butjitsiimpqrtant physical characteri'stic's anddimensi'ons should not vary more than minutely. p

,Still:further,zthe materialof which the stopper is made should not contaminate or affect the flavor ,of'....the..beverage contained in .the bottle, and conversely; ;,the,.beverage .should not affect the. stopper material; either chemically or physically .upon, eitherbrief. or continued contact. .,..-,In additionwto these' important considerations, there are-.thoseof simplicityof construction and easy andilogv ,expensejof .manufacture. These and;.the costtof. the; material) employed must be very 10wtocompete iththe v10w cost of known closurearsuch asthehcrowncap .Apropos ofltheidommercial aspects, a stopper, preferablyshlouldbeicapablehfibeing produced in 'val ll fcolorwandzitshould. be possible to imqn. makes useefiadisk stepper c mp d o cfilffiain materials. having;. critical characteristics and .dhnens Q stwhiehare,.such.that, when combined withJQj'QlZQOXQ having: dimensions and anglesspeciflcally related to,thecharacteristics and dimensions oi the disk; a c losure answering the above requirementsresults.

'I'lris and gtlger objects yvill become apparent ro is nsi s enantqi thed scri t o of the ntion in "conjunctiofiwith the drawings in Fig. '1 afcross seetmiiai" View" 6 showing the upper portion of a bottle having the stopper inserted;

Figs. 2 through 8 are enlarged fragmentary elevational views of the connection between the tab and disk;

Fig. 9 is a top plan view of the stopper shown in Fig. 1;

Fig. 10 is a vertical sectional view taken on lines IEIU of Fig. 9;

Fig. 11 is a vertical sectional view taken on lines H-H of Fig. 9;

Fig. 12 is a longitudinal sectional view of the neck of a bottle showing the stopper of Fig. 1 applied thereto;

Fig. 13 is a top plan view of the bottle closure shown in Fig. 12;

Fig. 14 is a top plan view of a modification of the invention;

Fig. 15 is a side elevational view of the -stopper shown in Fig. 14;

Fig. 16 is a top plan view of the stopper of Fig. 14 showing the ring extended;

Fig. 17 is a view similar to Fig. 11 of a modification of the invention;

Fig. 18 is a perspective view of a further modification of the invention; and

Fig, 19 is a vertical sectional view showing a sanitary covering for said bottle.

The preferred structure shown in the drawings consists of a bottle of glass or the like, the neck of which is illustrated and which is formed with an internal groove providing an outwardly flaring shoulder and an inwardly turned abutment. Cooperating with the bottle is a stopper constructed from a flexible material having a flat plane disk form and of a larger diameter than the maximum diameter of the internal groove. The disk is adapted to be cupped and forced into the groove to bring the lower marginal portion of said disk into engagement with the shoulder and the edge of the disk into engagement with the abutment.

Overlying the disk is a pull tab in the form of a ring, also constructed of flexible material, which tab is spaced from the disk proper throughout the greater portion of its extent and which may be attached to said disk in any one of several ways. The preferred manner of attaching the tab is by means of a connectorintegral with the disk and with the tab and of the same material as both. The tab is readily accessible and, when a finger is inserted in the same and the tab is pulled, the stopper may be withdrawn from the groove in the bottle to open the bottle. This arrangement and modifications thereof will be described below.

A sectional view of a bottle having such a stopper inserted therein is shown in Fig. 1 of the drawings. The bottle has a neck 30 which is formed with the usual opening 32 by which access to the interior of the bottle may be had. It

is to be understood that the invention is believed to have its greatest use as a' closure for bottles and cans, but it is conceivable that the stopper would have application in other passageways, the ingress-egress portions of which must be blocked with a stopper of some type.

With the receptacle illustrated the rim 34 of the neck is somewhat enlarged and is formed with an internal groove 36. This groove is so constructed as to provide an outwardly flaring shoulder 38 and an intumed angular abutment 40. This construction provides a lip 42 which overlies the shoulder 38. The lip 42 is formed with an inverted frusto-conical surface 44 which 4 serves as a funnel and directs the stopper into closing position and meets the surface 40 along the annular corner 46.

The stopper is indicated generally by the reference number 48 and in the preferred embodiment is formed of a disk 50 shown in Figs. 9, 10 and 11. This disk is of a suitable flexible material and is of a larger diameter than the maximum diameter of the groove 45. It is to be understood that it is within the scope of the invention to have the disk stopper normally cupshaped, but the preferred embodiment is a plane disk which becomes cup-shaped only when inserted in its groove. The disk stopper has a marginal portion 52 formed With a circular edge 54 at right angles to an undersurface 56.

Overlying the disk 50 is a pull tab 53 which is alsopreferably constructed of a resilient material and which, in the preferred embodiment, is spaced parallel from the disk 50 being connected at one point. This tab is in the form of a ring having a hole 60 in-the center thereof and so that the finger of the user may be inserted therein during removal of the stopper. The tab 58 may be of any convenient diameter and preferably of a diameter suificient to permit a finger to be easily inserted into the hole 59. In the drawing, the tab has been shown as disposed within the confines of the disk when the disk is in its plane configuration. However, a larger tab may be used even of such dimensions as to bring the extent of the tab outwardly of the edge 54 of the disk. In either case, the hole 69 in the tab exposes the center of the disk. Between the disk 50 and the tab 58 is a connector 62 which is also constructed of flexible material and which is integral with both the tab 58 and the disk 59. As shown in the preferred embodiment of the invention, the tab connector and disk are all of the same material.

The stopper is inserted into its groove in the following manner: After the receptacle has been filled, the disk 50 is laid across the upper end of the neck 30 resting on the lip 42. A plunger is passed through the hole 69 in tab 58 and pressed downwardly upon the center of the disk 50. A spheroidal shaped plunger such as illustrated in outline at 3| in Fig, 12 may be employed for this purpose. This downward movement causes the disk to cup and the under surface 56 thereof, at the marginal portion 52, to ride inwardly along the surface 44 of the lip 42.

When the edge 54 of the disk clears the inner corner of the lip 42 the marginal portion springs outwardly and the same snaps into groove 46 with the surface 56 of the marginal portion seated on the shoulder 38 and the edge 54 bearing against the abutment 40. This effects a seal and prevents leakage.

In the removal-of the stopper, the tip of a finger is inserted into the hole 60 in the tab 58 and the tab is elevated sufficiently to permit of inserting the finger well into said hole. Where an extremely small closure is desired, and as a result a tab having a small hole is used, a pencil or other similarly shaped article may be used instead of the finger. After insertion, a pull on the tab in a direction away from the connector 62 will quickly disengage the adjoining portion of the edge 54 of the stopper from the abutment 40, and break the seal formed at the edge of the stopper. The stopper can then be partially removed to permit pouring the contents out of the receptacle, or the receptacle can be inverted so as to let gas pressure force out the liquid contents. When the tab is released, the disk will either snap back into closing position or can easily be pushed by finger pressure into closing position to thus restore the seal. If desired, the stopper can be completely removed by continuing the pull on the tab.

In the preferred embodiment of the invention, the groove of the bottle neck in which the stopper sits has a particular configuration which has been found to be very satisfactory for retaining a disk of comparatively small dimensions at very high internal pressures. It must also be noted that the surfaces of the groove should be very smooth so that a gas-tight seal will be formed between the groove and the disk. The surface of the shoulder 38 is inclined downwardly and is approximately 45 from the axis of the egress of the bottle. The abutment 40 intersects the shoulder surface 38 at approximately right angles. These angles are shown in the broken lines in the life side of Fig. 1, and are designated by the reference letters A and B respectively.

The angular relationship of the groove sur: faces shown in Fig. 1 is preferred, but it is to be understood that the angular relationship can be varied without departing from the scope of the invention. Variance in the angular relationships will necessitate changes in the dimensions of the stopper where it is desired to hold the same pressure in the receptacle. For example, if the angle B is maintained constant and the angle A is increased, it will be easier for the stopper to be forced out by the internal pressure in the bottle. Accordingly, it would be necessary to increase the thickness of the disk 48 in order to increase the strength of the stopper and its resistance to being forced out.

On the other hand, it is possible to maintain angle B constant while decreasing angle A toward Such a decrease in angle A would permit a disk ofless thickness to be used in order to maintain the same pressure in the receptacle. It has been found, however, that a substantial decrease in the angle A will make more difficult the removal of the stopper and, therefore, decreasing that angle to any considerable extent has been regarded as unsatisfactory.

It is to be understood also that angle B can be varied and the same considerations discussed above in connection with angle A will apply. It

has been found that angle B can be increased by almost 45 although the thickness of the disk will have to be increased accordingly.

Likewise, the angle B can be decreased by almost 45 but such a decrease makes the stopper increasingly more difficult to remove from the bottleneck.

It will be observed that, when the disk 50 is seated in its groove as specified above, the internal pressure on the under surface 55 of the disk will cause the edge 54 to be forced tightly againstthe abutment 40 to form a gas-tight seal. Also the marginal portions of undersurface 56 will form a seal with the shoulder 38.

The changes in the angles mentioned above will change the radius of curvature of the stopper and also the deflection of the stopper. Knowing these characteristics, it is possible to calculate the necessary dimensions of the disk in order to withhold a predetermined pressure by using the formula to be discussed below.

InFig. 1 the. radius of curvature of the disk is indicated; by the letter R. The deflection is the distance a point; atthe center of the disk moves unden'infiernalpressure, when it changes from its normal position in the stopper'to a position in which the disk is just about to reverse its concavity and be forced out of the groove. This deflection is indicated by the letter D. The dimensions of the disk can be calculated for a predetermined internal pressure by the following formula taken from Machinerys Handbook, 14th Edition, page 414.

. the deflection will be correspondingly decreased.

Referring to the formula, when the deflection is decreased, then the thickness must be increased to maintain a constant relationship among the factors in the formula.

Thus any change in the angular relationships discussed above will require a change in the dimensions of the disk. The change in dimension can be computed by determining the effect that the angular change has on the radius of curvature and deflection, and applying new values of these factors to the formula.

The type of material from which the disk, its connector, and the ring. are to be formed is of the greatest importance, since. as mentioned, there are a considerable number of factors which must be taken into consideration.

The formula demonstrates the. importance of the modulus of elasticity. Depending on the use to which the receptacle is put, the stopper may be subjected to temperatures ranging from -40 F. to at least F. (the approximate temperature for the pasteurization of beer). In the beer industry, however, the range would have at its lower limit 26 F., the freezing point of beer. For a stopper disk one-sixteenth of an inch thick, the modulus of elasticity shouldnot be substantially less than 5,000 p. s. i. for the highest temperature with which the. stopper is to be used. It will be seen from the: formula, that when a material having a. much lower modulus is used (for example, 1-1000 p. s. i.), the thickness of the disk must be, increased and will become undesirably large andunwieldy, as well as more expensive.

On the other hand, the stopper must be sufficiently flexible so that it can be relatively easily removed from its bottle neck. This: flexibility must be maintainedeven at temperatures below freezing since it is not unlikely that. the beverages with which the stopper isusedwill undergo a certain amount of refrigeration.v The modulus of elasticity at the lowest; temperature to which the receptacle will be subjected should: not be substantially in excess of 130,000. p. s. i. for a disk having the giventhicknessof one sixteenth of an inch. If the modulus isv much greater, for example, over 200,000p. s. it'will be difficult to remove the stopper from. the bottle or the disk will have to be made undesirably thin.

In the process of insertingthe. stopper into its seat and during its removal from the: seat, the stopper undergoes rather severe bending stress. Therefore, the stopper must be capable of resisting a considerable bending without tearing. If

a strip of material .075 inch thick can be folded double on itself without tearing at 40 F., the material should be satisfactory in this respect.

Since it has been found desirable to make the stopper, the tab and the connector between the two of the same material, molded integrally, the material must have a tensile strength sufiicient to withstand the removal pull in order to prevent breakage during the pulling of the tab from the bottleneck.

Because stoppers of this type have to undergo large variations in temperature, it is also important that the coefiicient of thermal expansion should be low and should not exceed approximately 10 10- inches per inch per degree Fahrenheit.

The stopper must also resist pasteurization temperatures which with careless controls may run as high as 170 F.

Another most important characteristic of the material is that it must have a smooth texture in order to form a gastight seal where the disk engages its groove seat. Rubber, for example, is wholly unsuitable in this respect because of the grainy texture of its surface which does not permit the stopper to withstand high internal pressures.

The construction of the pull tab is very important to a successful operation of the stopper. In order to place a stopper in a bottle in such a manner as to maintain a comparatively high pressure in the bottle, it is obvious that the stopper must be secured very firmly in the bottle neck. When the stopper is thus applied firmly to the bottle neck, it is naturally rather difficult to remove. This is as it should be since the stopper would not be satisfactory if it could be easily removed. Therefore, considerable tension stress must be placed on the pull tab in order to remove the stopper from its seat in the bottle neck.

As shown in Figs. 2 and 3, if the disk 53, the connector 62, and the tab 58 are joined together at substantially right angles, the right angle joints form locations of stress concentration and a pull on the tab will have a tendency to tear the tab away from its connector at those joints. The tear which results is illustrated at 64 in Fig. 3.

A solution to this difficulty is shown in Figs. 4 and 5. Instead of right angle joints, as shown in Fig. 2, the joints are formed with fillets having curved surfaces 66, as illustrated in Figs. 4 and 5, and these fillets should have an optimum radius equal to the thickness of the ring, but it can be as low as inch for a ring of inch thickness, for example. It will be seen from Fig. 5 that pulling on the tab, having such fillets, results in no undesirable stress concentrations. Fig. 6 shows the ring and disk connection in a different view taken in the direction of lines 66 of Fig. 4. Fig. 6 shows similar fillets 68.

In the removal of the stopper from the bottle neck, it will be appreciated that the greatest leverage would result from placing connector 62 out as far toward the edge of the disk as possible. Such a connection is shown in Fig. 7. While, at first blush, this would appear to be the most desirable arrangement, it is actually so disadvantageous as to render a stopper so constructed almost completely useless if pressures much greater than one atmosphere are to be retained in the receptacle. The additional mass of material caused by the connector 62 at the edge of the disk causes a distortion or deformation of the disk at its edge. This deformation results in the wavy lines 10 in the edge portion of the disk as 8 shown in Fig. 8. These wavy lines make it impossible to form a seal which will withstand the pressures encountered, for example, in the beer bottling or carbonated beverage industry.

In accordance with the invention, therefore, the connector 62 is located in a specially chosen position which is spaced from the edge of the disk but which is also spaced as far as possible from the center of the disk so as to provide good leverage in the removal of the stopper. Thus, the connector should be spaced from the edge of the disk far enough to prevent distortion but as far from the center as possible as to provide good leverage. Spacing the connector from the center at least two-thirds of the radius of the disk is preferred.

These are the mechanical characteristics and are most important to a successful stopper. However, in order to be a commercially successful item, the stopper must meet additional standards. For example, the material must be such that it will not contaminate the food or beverage contained in the receptacle and, in turn, it must not be adversely affected by the material in the receptacle. It has been found that, if the material can withstand the effects of weak acids and bases, the material will be satisfactory.

In order to have high speed production, it is very desirable to use a plastic which can be injection molded. By so forming the stopper it has been found that a substantial number can be formed in a short time.

As has been indicated, in order to go into competition with existing closures, it is necessary to have a closure which can be produced at very low cost. For this reason materials which presently cost several dollars per pound and might be satisfactory in all other respects would be out of the question on a cost basis.

Additionally, where materials are equal in all respects including cost per pound but have widely differing specific gravities, the material with the lowest specific gravity will be preferred for it will provide the most stoppers per pound.

These physical and chemical characteristics which have been discussed above rather limit the material which can be used. The inventors have experimented with a considerable number of materials, including rubber and many plastics, and have found polyethylene to be the material which meets all of the standards. They have also found among the vinyl resins an improved Vinylite which, while being 50% heavier than polyethylene, nevertheless would be satisfactory. The vinyls, however, are subject to the difiiculty that they must be compound with plasticzers. Initially the product is satisfactory but after a period of time, the plasticizer leaches out and the material becomes brittle.

Other materials which are acceptable from the standpoint of their physical characteristics are nylons 10001, 3001 and 6501, Teflon and Kel-F. The latter two are polytetrafiuoroethylene and polymonochlorotrifiuoroethylene respectively. At present the cost of these materials is considerably higher than polyethylene.

Polyethylene, in addition to having the desirable characteristics mentioned above, is also advantageous in the manufacture of a commercially salable product in that color can be added to the material without its losing any of its necessary properties. Further, it is possible to mold a trade-mark in the material, thus avoiding the printing of a trade-mark as is done on presentday crown caps.

It, is; realized that, particularly with: the, great development work now some. on in. pl st c ad:- ditional; materials probably will, become: available in future. years. Accordingly, the inventors wish. it to be understood that they do not, want to. be limited to polyethylene or the other listed plastics, rather, the inventioncoverssthose ma? terials which fall within. the scopev of the above described physical and chemical characteristics.

The applicants. have constructed a bottle.- and closure arrangement which. has-been completely satisfactory and has the following dimensions: diameter of the disk, it of an inch;v thickness of the: disk, of an inch; shortest, radial distance from outer edge toconnector, V; of an; inch; bottle neck dimensionmaximum groove diameter. 11% of an. inch, angle A, 45.; angle B, 90".

The stopper placed in. a bottleneck; of. the above configuration has a radius of curvature of approximately of an inch and a deflection oi approximately -52 of an inch.

The stopper is made from polyethylene whose physical. and chemical characteristics as well as the cost of the material make it satisfactory in every respect.

While the preferred embodiment of the invention has, been described, it is. to be understood that modifications can. be made the preferred embodiment without departing from the scope of the invention. Certain additional embodiments be described in connection with Figs. .3: to 1.9;.

Wherea, small stopper i desired, difficulty may be occasioned in inserting the finger into the hole of the ring for the purpose of withdrawing the stopper. To eliminate this objection, a modifled form of stopper, as shown in Figs. 14, 15 and 16, may be employed. This stopper is similar to the stopper originally described, the construc tion shown in Figs. 14 to 16 differing solely in the ring 83. This ring is constructed with two return bends 3| and 82 opposite the connector 52 which terminate in a loop 83 located within the confines of ring 8 The loop 83 may project somewhat above the major portion of the ring to as shown in Fig. 15 whereby the same may be readily engaged by the finger. In the use of this form of the invention, the loop 83 is raised and swung upwardly. At the same time, the finger is inserted in the hole 86 and the loop stretched out. The ring would then appear as shown in Fig. 16 giving ample space for the reception of the finger. Withdrawal of the stopper would then be accomplished in the same manner as in the other form of the invention.

In Fig. 17, another form of the invention is illustrated. The construction shown in Fig. 17 is similar to that shown in Fig. 1, the principal difference being in the connection of a pull tab St to the disk 48. In this form of the invention, the central portion of the connector and the corresponding portion of the pull tab ring have been dispensed with, forming two smaller connectors 9! and 92 instead of the single connector. These two connectors have the fillets described above in connection with Figs. 2 through 8 which prevent the pull tab from being broken loose from the disk 48 and forming the connecting means of the stopper.

A still further embodiment of the invention is shown in Fig. 18. In this form of the invention, a disk its has attached thereto a pull tab ll)! of a material different from the material of the disk. For example, the pull tab could be made from some type of fabric. In the molding of the stopper, the pull tab is molded into the Pl ne 1: the di h .5 .12: s stem the broken lines ud it t. 1.0.2..

t l. ans. w mbodiment- Qt: the nven o is sh wn. Iam i m si y e desira le. to at an old aroun t e mouth. of the; receptacle to: which, the stopper is applied. such $hi 1d s-sh wu in la a11- plied, to a; stoRPBf: similar to.- thatshown; in Fig. h unne fi ure ha n ed. int grallytherewith a thin film H9 wh h extends an around he arg nal portion f; the; d sk. Inv t eurocess ins rtin the sto perint t bottle, this. film; -0 can; be; disposed around the m t oi. the battle as; shown. in Fig. 19;, thus, forming a sanitary protective, covering.

An. alte ative oi e construct on shown in 19 would be a t -iia film; cover n e ely pe nd hatch o the bo tl This film c d. be app! 1- very imply by pouri a large bu ble. of flu d: P as ic material aro nd; e op of he. resemb e ether; the s o er e 1 sorted.

It is to: be underst od tha the s pperac r s. t emes .m e it on be; us d t rracuum s aled; re p cles by r ver i he. ent o o t e annular groove and y reversin the c c r ty o t e dish to. a d i t's. position.

Changes the emit c form; o he inv ntio as. herein descr ed; may a -made with-in the scope of what-.- isclaimed with ut depa tin fr m he p r h invention.

We, claim; a

1 A rn r fur a. recepta e tor b en. c b n.- ated beverages and the like and having an outlet portion formed with an internal annular groove providing an outwardly flaring shoulder and an inwardly turned abutment; said stopper comprising; a fiat circular disk having substantially the same cross sectional configuration through all diameters thereof, said disk adapted to be cupped in the groove of smaller diameter than said disk with the marginal portion thereof seated on the shoulder and with the edge thereof engaging the abutment of the groove to form a seal, and a molded pull tab integrally joined to said disk at a location spaced from the edge thereof a distance sufficient to provide uniform contact of its edge portion when in sealed position and spaced also at least one-half the radial distance from the center of said disk to enable said disk to be opened upon pulling said tab by first raising the edge of said disk away from its groove along a limited arc radially outwardly from said tab, said disk and tab being formed of a synthetic thermoplastic polymer, and said disk having the properties of resilience sufficient to permit its forceable entrance and withdrawal from the receptacle, a stifiness sufiicient to prevent its removal due to internal receptacle pressures normally encoun tered in bottle beer and carbonated beverages, a substantial resistance to liquid absorption, and being substantially inert to beer and carbonated beverages.

2. A stopper according to claim 1, in which the distance of the tab from the edge of said disk is greater than the thickness of said tab, and in which the distance of the tab from the center is at least two-thirds the radius of the disk.

3. A stopper according to claim 1, in which said pull tab comprises a ring, and a connector block attaching said ring to said disk, said block having fillets located at the joints between said block and ring and said block and disk.

4. A stopper for a receptacle having an outlet portion formed with an internal annular groove thickness of said tab to provide uniform contact of its edge portion when in sealed position and also at least two-thirds the radial distance from the center of said disk.

5. A stopper according to claim 4, in which said disk is of uniform thickness.

6. In combinaation, a receptacle for beer, carbonated beverages and the like and having an outlet portion formed with an internal annular groove providing an outwardly flaring shoulder and an inwardly turned abutment, and a stopper, said stopper comprising a flexible disk having substantially the same cross-sectional configuration through all diameters thereof, said disk having a diameter greater than the diameter of said groove and being inwardly dished with the marginal portion thereof seated on said shoulder and with the edge thereof engaging said abutment, and a molded pull tab integrally joined to said disk at a location spaced from the edge thereof a distance sufficient to provide uniform contact of its edge portion when in sealed position and spaced also at least two-thirds the radial distance from the center of said disk, said disk and tab being formed of a synthetic thermoplastic polymer, and said disk having the properties of resilience sufficient to permit its forceable entrance and withdrawal from the receptacle, a stiffness sufficient to prevent its removal due to internal receptacle pressures normally encountered in bottled beer and carbonated beverages, a substantial resistance to liquid absorption, and being substantially inert to beer and carbonated beverages.

7. The combination according to claim 6, in which said abutment is inclined approximately 45 to the axis of said annular groove and in which said shoulder intersects said abutment at approximately 90.

8. A stopper according to claim 1 in which said synthetic thermoplastic polymer is polyethylene.

MARSHALL B. BEAUBAIRE. MARTIN E. STRAND.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 327,099 Painter Sept. 29, 1885 528,486 Painter Oct. 30, 1894 625,197 Phillips May 16, 1899 1,437,572 Vons Dec. 5, 1922 1,840,889 Duncan Jan. 12, 1932 2,396,337 Moore Mar. 12, 1946 2,487,400 Tupper Nov. 8, 1949 

